JPH01104829A - Acrylic fiber having excellent water-absorption and mechanical property - Google Patents

Abstract

PURPOSE:To provide the titled fiber having multilayer structure consisting of two or more kinds of laminated acrylic polymers including acrylic polymer containing carboxyl group and having specific properties and improved adhesivity, tackiness and mechanical strength of swollen fiber. CONSTITUTION:The objective fiber has a multilayer structure consisting of two or more kinds of acrylic polymers including an acrylic polymer containing carboxyl group and bonded with each other along the fiber axis to form two or more layers, wherein said carboxyl-containing acrylic polymer has a carboxyl group content of >=0.3m-mol/g and a water-retention of >=50wt.%. The fiber is produced preferably by separately dissolving a carboxyl-containing acrylic polymer and the other acrylic polymers in organic solvents, dividing the obtained spinning dopes into layers with a layer-dividing apparatus, spinning e.g. by wet spinning and treating with an alkali.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to acrylic fibers having excellent water absorbency and mechanical properties.

[Prior Art] Attempts to impart water-swellability to acrylic fibers were known prior to the filing of the present application. For example, JP-A-57-139510 discloses that special acrylic IJAN can be made by boiling acrylic fibers containing a carboxylic acid component in an alkaline aqueous solution to impart water swelling properties to the fibers. .

However, conventional water-swellable acrylic fibers have lower mechanical strength than normal acrylic fibers, especially after being made water-swellable (generally treated with alkali), and have insufficient dyeability. This is because water-swellable acrylic fibers are difficult to crimp properly, including the fact that they tend to feel sticky due to water absorption.

There were various problems such as difficulty in obtaining a bulky texture.

[Problems to be Solved by the Invention] In order to solve the problems of water-swellable acrylic IA fibers, the present inventors have developed a multi-layered composite technology of acrylic fibers (Japanese Patent Application No. 1983-1999), which was proposed previously. 170742) and found that the above problems could be solved all at once.
This has led to the present invention.

That is, an object of the present invention is to further improve the mechanical strength, adhesiveness, "stickiness", dyeability and bulkiness of water-swellable acrylic fibers.

[Means for Solving the Problems] The above-mentioned object of the present invention is to provide a multilayer structure in which two or more types of acrylic polymers including a carboxylic acid group-containing acrylic polymer are joined to a length of 2 m or more along the fiber axis direction. structure, the carboxylic acid group content of the carboxylic M group-containing acrylic polymer is 0.3 mmol/'j or more.

This can be achieved by using acrylic fibers with excellent water absorption and mechanical properties, characterized by a water retention rate of 50% by weight or more.

In other words, the multilayer structure of the fiber of the present invention is a structure in which a normal acrylic polymer and a carboxylic acid group-containing acrylic polymer are continuously laminated along the fiber axis direction, as shown in the cross-sectional photograph in FIG. The number of layers is 2 or more, preferably 2 to 1
This means 0 layers, preferably 3 to 6 layers. At this time, it is desirable to have a multilayer structure in which at least one layer of an acrylic polymer other than the carvone M group-containing acrylic polymer is arranged on the fiber surface.

By adopting such a multilayered structure, the fibers of the present invention not only maintain mechanical strength after water absorption treatment and move extremely effectively, but also reduce adhesion between single fibers and the "sticky feeling" after water absorption. ” can be resolved.

That is, in the fibers of the present invention, the carboxylic acid group-containing acrylic polymer is made hydrophilic and crosslinked by water absorption treatment with an aqueous alkaline solution, but on the other hand, ordinary acrylic polymers are not affected by alkali and therefore do not meet the desired expectations. As a result, the mechanical strength can be maintained. In addition, the multilayered structure of the fibers of the present invention works to improve dyeability, and at the same time, if the difference in shrinkage performance between the component polymers (especially in alkali) is controlled, crimping suitable for bulky texture can be achieved. It can be made manifest.

Further, in the fiber of the present invention, the carboxylic acid group content of the carboxylic acid group-containing acrylic polymer in the fiber is 0.3 mmol/g or more, preferably in the range of 0.4 to 2.0 mmol/9. If the carboxylic acid group content is 0゜3mlO1/
If it is less than 9, the water absorption performance is insufficient and it cannot be used as a water-swellable fiber.On the other hand, if it is too high, the spinability will be poor in spinning acrylic polymers, and the fibers will not adhere to each other after alkali treatment. The fiber properties tend to deteriorate, making it difficult to obtain good fibers.

Furthermore, the fiber of the present invention has a water retention rate of 50% by weight or more.

It should preferably range from 100 to 500% by weight. If the water retention rate is less than 50% by weight.

For the same reason as in the above case, it cannot be used as a water-swellable fiber, and on the other hand, m
It is difficult to obtain fibers, and there is a tendency for stalemate to occur.

The carboxylic acid group content and water retention rate herein are defined as follows.

Carboxylic acid group content @ (mmol/L): Accurately weigh 1 g of a sufficiently dried sample (Ag), add 200 ml of water to it, and then add 1N hydrochloric acid aqueous solution while heating to 50°C to adjust the pH to 2. Then, a titration curve is determined using a 0.1N aqueous sodium hydroxide solution according to a conventional method. This titration curve shows that the caustic soda aqueous solution ffi (B
Find d).

From the above measurement results, the carboxylic acid group content was calculated using the following formula.

Water retention rate (%): Cut the sample fiber into a length of about 50 to 7Qmm, and
Soak in water at 25°C for 1 hour. After the time has elapsed, put it in a polyester cloth (200 mesh) and put it in a stretch dehydrator (
The moisture between the fibers is removed by rotating the fiber at 35,001'l) using an inner diameter of 180 mm.

The weight (old) of the sample thus prepared is measured.

Next, the sample is dried in a vacuum dryer at 80° C. until it reaches a constant weight, and the weight (W2) is measured.

The water retention rate (%) was calculated from the above measurement results using the following formula.

Next, an example of manufacturing the fiber of the present invention will be explained.

As the carboxylic acid group-containing acrylic polymer in the present invention, an acrylic polymer mainly composed of acrylonitrile and a carbon ill-containing vinyl monomer is preferably used.

In this case, the carboxylic acid group-containing vinyl monomer is acrylic acid, methacrylic acid, or itaconic acid.

Maleic acid, crotonic acid, butenetricarboxylic acid, etc. may be mentioned, but acrylic acid, methacrylic acid, and itaconic acid are particularly preferably used alone or in combination. Of course, the content of the carboxylic acid group-containing vinyl monomer is 0.3 uol in the carboxylic acid group-containing acrylic polymer.
/y or more, preferably 0.4 to 2.0 mmof/g.

In addition to the carboxylic acid group-containing vinyl monomer, the copolymerization components of the carboxylic acid group-containing acrylic polymer include, for example, lower alkyl esters of acrylic acid and methacrylic acid, acrylamide, methacrylamide, vinyl acetate, vinyl chloride, styrene, Vinyl compounds such as vinylidene chloride, vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid.

Similar or different types of acidic acids such as unsaturated sulfonic acids such as p-styrene sulfonic acid and their salts can be used. However, the mother is about 15
It is desirable to keep it within mol%.

On the other hand, acrylic polymers other than carboxylic acid group-containing acrylic polymers include known acrylic polymers having fiber-forming properties, that is, modacrylic polymers containing 30 mol% or more of acrylonitrile (hereinafter abbreviated as 8N). or acrylic polymers containing 80 mol% or more of AN, and copolymers thereof.

In general, when selecting two or more component polymers for the fibers of the present invention from the viewpoints of water absorption, mechanical strength, dyeability, crimp development, adhesiveness, etc., carboxylic acid group-containing acrylic that undergoes hydrophilic crosslinking with an alkali is selected. The copolymerization content of the system polymer is desirably in the range of about 1 to 10 mol%, particularly 3 to 8 mol%.

If the copolymerization amount is less than 1 mol %, hydrophilic crosslinking in alkali tends to decrease and water absorption (water retention) tends to decrease. On the other hand, if it exceeds 10 mol %, the mechanical strength and crimp development properties of the fibers decrease, and the fibers tend to adhere to each other, making it difficult to obtain crimp development properties suitable for a bulky texture.

The copolymerization content of acrylic polymers other than carboxylic acid group-containing acrylic polymers that hardly undergo hydrophilic crosslinking with alkali is about 1 to 10 mol%, particularly 2 to 9 mol%.
A range of is desirable.

If the copolymerization amount is less than 1 mol%, the spinnability and dyeability will decrease, making it difficult to obtain the desired fiber, while if it exceeds 10 mol%, the mechanical strength, dyeability, and crimp development of the fiber will decrease. It is difficult to obtain fibers that are suitable for the texture and bulky texture.

The above-mentioned carboxylic acid group-containing acrylic polymers and other acrylic polymers include dimethylformamide, dimethylacetamide, dimethyl sulfoxide (hereinafter abbreviated as D) fsO), and alkali metals such as rhodan lithium, rhodan potassium, and rhodan sodium. It is dissolved in organic and inorganic solvents such as rhodan salt, rhodan ammonium, zinc chloride, perchlorate, etc., and the polymer concentration is about 10~10.
The spinning dope has a 25% type groove.

This spinning dope of two or more polymers to be multilayered is supplied to a multilayering device, separated into layers, and then mixed.

Fibers are formed by a wet spinning method in which the fiber is discharged from a single spinneret hole into a coagulation bath, or by a dry-wet spinning method in which the fiber is once discharged from the spinneret hole into air or an inert atmosphere and then introduced into a coagulation bath.

FIG. 2 is a flow sheet for explaining the process requirements around the spinning bath for the fiber of the present invention. A in the figure.

B is a spinning dope for a multilayer polymer, 1 is a guide device for individually introducing the spinning dope for a multilayer polymer, 2 is a multilayer device, 3 is a filter, 4 is a spinneret, and 5 is a coagulation bath.

What should be particularly noted in the step of spinning the fiber of the present invention is that the spinning dope of the multilayer polymer is first sufficiently and stably divided into layers by the multilayering device, and the multilayered state formed is transferred to the spinneret hole. The aim is to maintain stability until the end.

That is, in order to achieve sufficient multilayering in a multilayering device, the theoretical number of layers in a single yarn is divided into 3 or more, preferably 4 to 15, more preferably 5 to 12, and then transferred to a single spinneret. It is to introduce.

The theoretical number of layers in the single yarn may be appropriately controlled by the structure within the multilayering device, that is, the number and arrangement of stacked layers of the multilayering element, the twist angle of the twisting blades, the number of two-pass tubes, the number of holes in the spinneret, etc. .

By maintaining the theoretical layer number in a single yarn within this range, it is possible to significantly improve mechanical strength, adhesion, sticky feeling after water absorption treatment, color development after dyeing, bulkiness, etc.

The theoretical number of layers in a single fiber here refers to the statistically average number of layers of inflowing solution per spinning hole of a spinneret, and is the theoretical value of the number of layers that can theoretically enter a single fiber in a completely layered region. It can be determined by a quadratic equation.

In the above formula, K is a constant determined by the outer shape of the spinneret; for a rectangular spinneret, the value of K is 1, and for a circular spinneret, the value of K is 1.1.

Next, in order to stably form a multilayered polymer spinning dope into multiple layers in a multilayering device, it is desirable that the viscosity difference between the spinning dope be 50 voices or less at 60°C. By setting this viscosity difference to 50 poise or less, the streamlines are not easily disturbed in the multilayering device, and the multilayer state divided into two layers becomes more stable.

Furthermore, when supplying the spinning dope to the multilayering device, the spinning dope to be multilayered is once combined.

Rather than supplying the spinning dope to the multilayering device, each spinning dope to be multilayered is individually injected through a dope guide device (inflow port) installed at the inlet of the multilayering device, as shown in Figure 2, so that they do not mix with each other. It is desirable to This inflow means for the spinning dope is completely different from the effect of simply reducing the number of multilayering elements by one, and allows multilayering to be performed reliably and stably within the multilayering device.

Generally, the multilayering device has a pitch (L/D) of the multilayering elements of 0.8 to 2.5 degrees, especially 1.4 degrees, as shown in FIG.
It is desirable that it be within the range of ~2.0.

If this pitch deviates from 0.8 to 2°5, the streamlines of the spinning stock solution multilayered in the multilayering device will be disturbed.

The multi-layered state will become unstable and you will win.

The multi-layering device used here includes, for example, the "High Mixer" manufactured by Toshishiki Co., Ltd., the "Static Mixer" manufactured by Noritake Co., Ltd., and the "Skeya Mixer" manufactured by Sakura Seisakusho Co., Ltd.
, "Paros ISO Mixer" manufactured by Tokushu Kakoki Co., Ltd.

Among these multilayer devices, the constituent elements are not complicated, the flow resistance of the spinning dope is relatively small, and there is little change in the effective cross-sectional area in the spinning dope flow path.In other words, there is no abnormality in the spinning dope within the device. "Static mixers" and "Skeya mixers" that do not easily cause stagnation are preferably used.

The spinning dope that has been divided into layers into predetermined ranges by the multilayering device described above is
Instead of a spinneret for composite spinning, the spinneret is introduced into two ordinary single spinnerets, and discharged into a coagulation bath using the aqueous solution of the organic or inorganic solvent as a coagulant.

At that time, the polymer solution discharged from the spinneret may be directly introduced into the coagulation bath (wet spinning method), or the spinneret may be placed at a position 2 to 20 mm above the surface of the coagulation bath and the spinneret hole The spinning stock solution discharged from the spinning dope is introduced into the coagulation bath after traveling through a microscopic space between the spinneret hole and the coagulation liquid surface.

A so-called dry-wet spinning method may also be used.

In carrying out the present invention, the opening between the multilayering device and the spinneret is 10 μm or more, preferably 20 μm or more.
It is desirable to interpose a filter of about 50μ,
The filter media is generally made of gauze fabric made of polyester, polyamide, etc., or stainless steel wire mesh. Furthermore, it goes without saying that the fibers of the present invention can be obtained by dry spinning.

The coagulated yarn derived from the coagulation bath is subjected to treatments such as washing with water or stretching simultaneously with water washing, washing with water after stretching, or stretching after washing with water, and then dried to become denser and mechanically crimped.

The fibers thus obtained are subjected to alkali treatment at any stage, including the fiber threads, yarns, and knitted fabrics.

In this case, the alkali is, for example, a sodium carbonate aqueous solution, and the alkali concentration is about 19/j to 100 y/,
11. Preferably 5g/, 1! -509/1 aqueous solution, and the treatment temperature is about 70-100°C, preferably 85°C.
It is generally carried out at a temperature of ~100°C.

Under conditions exceeding the upper limit of this preferred range, the reaction rate between the carboxylic acid group-containing component layer of the multilayer composite fiber and the alkali becomes faster, and the water absorption performance is improved, but physical properties are significantly deteriorated and stagnation occurs. Also, under conditions below the lower limit of the preferred range,
The reaction rate between the carboxylic acid group-containing component layer and the alkali becomes slow, making it impossible to obtain the desired fiber with good water absorption (water retention).

In order to obtain the fibers of the present invention more effectively, the treatment in alkali is preferably carried out under tension.

In addition, after washing the fibers treated in alkali with water, 70 to 1
It is best to boil in hot water at 00°C for 1 minute or more, preferably 3 to 10 minutes.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

In this example, the number of crimp, degree of crimp, and color development after clear water treatment.

and bulkiness were determined as follows.

Number of crimp and degree of crimp after clear water treatment: Conforms to JIS-L1015.

Color development (K/S) Opened li! The dye is adsorbed on the fiber using a temperature rising dyeing machine under the following dyeing conditions.

Dyeing conditions: Dye Cathilon Blue GRL O,
5% owf Kajiogen 8N Super 1゜5% owf
Sodium acetate 0.5%owfpH=4
(Adjusted with acetic acid) Bath ratio: 1:100 Dyeing temperature: 1 hour The temperature was raised to 98°C in 60 minutes, dyed at 98°C for 60 minutes, and then slowly cooled. The reflectance (R) at a wavelength of 640 mμ was measured with a device, and the color development (K/S) was calculated using the following formula.

The bulky test fiber was opened and treated with clean water (100'CX 20 minutes)
Then I made bulky soup stock. After drying, sensory (touch) evaluation was performed.

Example AN 94.7 mol %, itaconic acid 3 mol %, methyl acrylate 2 mol % and 0.3 mol % of sodium methallylsulfonate.
Mol% was solution-polymerized in DMSO to prepare a spinning stock solution (A) having a solution viscosity of 120 voids/60° C. and a concentration of 21.8% by weight.

On the other hand, 94.0 mol% of AN, 5.5 mol% of methyl acrylate and 0.5 mol% of sodium methallylsulfonate were similarly solution-polymerized to obtain a solution viscosity of 125 poise/60°C and a polymer concentration of 22.3% by weight. A spinning stock solution (B) was prepared.

Equal amounts of the two types of spinning stock solutions (A) and (B) above are mixed in a "static mixer" equipped with a stock solution inlet guide device 1 as shown in FIG.
1.5) and layer-divided, a polyester gauze fabric filter (opening: approx. 30
μ) was discharged from a rectangular single spinneret with a hole diameter of 0.065 II 1 mφ into a coagulation bath containing a 55% by weight DMSO aqueous solution as a coagulation liquid to form a coagulated thread. At this time, the number of layers in the multilayer element and the number of holes in the rectangular single spinneret were appropriately controlled to obtain the theoretical number of layers in the single yarn as shown in Table 1.

Further, the spinning draft was 0.5, and the coagulated yarn take-up speed (spinning speed) was 10 m/min.

The coagulated yarn was drawn 5.5 times in hot water at 98°C, and after thoroughly washing the drawn yarn with warm water, it was dried and densified at 160°C.

This dry densified yarn is processed using a push-type crimper to produce approximately 11 strands/2
It was mechanically crimped in a volume of 5ml and dried with hot air at 70°C to obtain an acrylic fiber with a single fiber fineness of 3 denier.

Next, the above fibers were heated at a temperature of 98°C and
1 aqueous solution for about 30 minutes, washed roughly with water, and then boiled in hot water at 90° C. for 10 minutes.

(The strength and elongation, water retention rate, number of crimps, degree of crimping, adhesiveness and bulkiness of the q-treated fibers were investigated and shown in Table 1.

On the other hand, for comparison, only the spinning dope (^) was subjected to wet spinning and hydrophilic crosslinking treatment in the same manner as above to produce an acrylic fiber 1t having a single fiber fineness of 3d. The strength and elongation, water retention, number of crimps, degree of crimping, adhesiveness and bulkiness of the obtained fibers were investigated and are also listed in Table 1. In this case, a sodium carbonate 109/ρ aqueous solution was used for the hydrophilic crosslinking treatment.

As these results show, carbonffi! The acrylic polymer containing the acrylic polymer and the acrylic polymer other than the carvone Ml-containing acrylic polymer have a multilayer structure of two or more layers along the axis. In addition, it has an excellent water retention rate of A3 similar to that of conventional water-swellable fibers, and has no adhesive properties and has a bulky texture.

(Hereinafter, blanks) [Effects of the Invention] The acrylic fiber of the present invention as described above overcomes the drawbacks of conventional water-swellable acrylic fibers, particularly its low mechanical strength after being made water-swellable (generally treated with alkali). Various problems such as poor dyeability, insufficient dyeability, stickiness and adhesion due to water absorption, and bulky texture were all solved at once, and by utilizing the water swelling property. Blend products (canvas, filters) of this fiber and various fibers (e.g. polyester fiber).

(condensation prevention material, etc.), using its multi-port water absorption performance.

Diapers, sanitary products, soil improvement materials that utilize moisture retention ability, instant sandbags, sphagnum moss, and electrostatic flocking products.

It has remarkable effects in various fields of use, such as futon cotton.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional photograph of the acrylic fiber according to the present invention, Figure 2 is a flow sheet explaining the process requirements at the spinning stage of the fiber of the present invention, and Figure 3 is a schematic diagram of the multilayering element in the multilayering device. It is. A, 8: Multilayer polymer spinning dope 1: Multilayer polymer guide device 2: Multilayer device, 2-: Multilayer element 3: Filter 4: Spinneret D: Multilayer element diameter [: Multilayer element 1 piece length

Claims (1)

[Claims] A multilayer structure in which two or more types of acrylic polymers including a carboxylic acid group-containing acrylic polymer are joined together in two or more layers along the fiber axis direction, and the carboxyl group of the carboxylic acid group-containing acrylic polymer is An acrylic fiber having excellent water absorbency and mechanical properties, characterized by an acid group content of 0.3 mmol/g or more and a water retention rate of 50% by weight or more.